Multiple CTL subsets generated by H-2.L locus products stimulation: evidence for an antigenic determinant private to H-2.Ld

Analysis of the fine specificity of CTL subpopulations raised by an H-2.L locus products stimulation (H-2dm2 anti-H-2d) was performed by absorption experiments by using monolayers of macrophages of H-2m, H-2q, H-2b, and H-2k haplotypes. The results show the existence of four CTL subsets. The pattern of reactivity of three of them could be correlated with that of antibodies present in H-2dm2 anti-H-2d antisera (anti-H-2.64, anti-H-2.65, and anti-H-2.Kk). The fourth CTL subset reacted with a specificity unique to H-2.Ld molecules (a private specificity?), absent on cells from H-2m, H-2q, H-2b, and H-2k haplotypes, and undescribed as yet by serologic methods. These data support the hypothesis that the H-2.L locus products are comparable in their antigenic properties to those of the H-2.K and H-2.D loci.     

T cell responses to Mls determinants are restricted by cross-reactive MHC determinants

The studies presented here investigated the relationship between T cell recognition of MHC-encoded products and non-MHC-linked Mls determinants. The first aspect addressed whether Mls-reactive T cells recognize Mls-encoded products alone or in association with MHC-encoded determinants. Initial studies used Mlsa-specific T cell clones that were generated by repeated stimulation of C57BL/6 or B10.A(5R) spleen cells with DBA/2 lymphoid cells. These clones recognized Mlsa on cells expressing MHC products of the H-2b, H-2d, and H-2k haplotypes, but not the H-2q haplotype. Thus, these cloned T cells were found to recognize Mlsa products in association with public but demonstrably polymorphic H-2 determinants. The question of whether T cell clones that were specific for self-H-2 determinants (autoreactive) or soluble antigen plus syngeneic H-2 (antigen-specific) could also be stimulated by Mlsa determinants was also addressed. A substantial proportion of the antigen-specific or autoreactive T cell clones tested were stimulated by Mlsa determinants. Furthermore, stimulation of these clones by Mlsa was H-2 restricted. The pattern of H-2-restricted recognition of Mlsa by these clones was not distinguishable from that observed in the Mlsa-specific T cell clones, nor was it influenced by the primary specificity or H-2 restriction pattern of a given clone. Although these findings provide a means of explaining the observation that Mls-reactive T cells exist at extremely high precursor frequencies, they also raise questions regarding the nature of the receptor structures which are used by a single T cell in the recognition of two or more apparently distinct stimuli.     

Cellular interactions of L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)-specific suppressor factors. I. Inhibition of the activity of GAT-specific helper T cell clones by monoclonal GAT-specific suppressor T cell factors

Considerable information concerning the serology and biochemistry of antigen-specific, T cell-derived suppressor factors has been obtained with the use of T cell hybridomas as a source of homogeneous material. Similarly, knowledge of helper T cell products and receptors is accumulating from studies of helper T cell clones and hybridomas. Our strategy for studying the mechanisms by which suppressor factors inhibit responses was to determine whether monoclonal suppressor factors could inhibit antibody responses specific for L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) in cultures containing unprimed splenic B cells, macrophages, and GAT-specific T cell clones as a source of helper activity. The MHC-restricted, two chain suppressor factors, GAT-TsF2, inhibited these responses if the helper T cell clones and suppressor factor were derived from H-2-compatible mice. Furthermore, responses were inhibited by briefly pulsing T cell clones with GAT-TsF2 in the presence of GAT, indicating that suppressor factors need not be present continuously. In addition, helper T cell clones adsorbed syngeneic, but not allogeneic, GAT-TsF2 in the presence of GAT. Adsorption also requires a shared antigenic specificity between the H-2b-derived helper T cells and TsF2 factor. Thus, helper T cells can serve as the cellular target of antigen-specific, MHC-restricted GAT-TsF2, and cloned helper T cells can be used as a homogeneous target population for analysis of the molecular mechanisms of T cell suppression.     

The main difference between the repertoire of receptors of effector T-killers and their secondary precursors (memory cells)

Receptor repertoire analysis of in vivo induced secondary cytotoxic T lymphocyte precursors (pCTL-2) was performed, using the technique of their specific adherence to macrophage monolayers with subsequent elution of the adherent pCTL-2 and their activation by heat-killed donor stimulator cells. The capacity of anti-H-2Kb pCTL-2 receptors to contact H-2Kbm has been revealed only in a minor pCTL-2 component whose progenitors were able to lyse mutant bm1 target cells (TC). Unlike poor cross-reactivity of CTL descended from anti-Kb, pCTL-2 which were eluted from the donor monolayer, CTL-progenitors of anti-Kb pCTL-2 eluted from bm 1 or B10. A (4R) third-party monolayers lyse in equal quantities the donor TC and those third-party TC from which they have been eluted, but fail to lyse other TC. Enrichment of pCTL-2 eluted from bm 1 or B10. A (4R) monolayers is 6- or 12-fold lower, respectively, than after their elution from the donor monolayer. The findings indicate that anti-class I MHC pCTL-2 are separated into fractions, with their receptors being strongly specific (with high affinity) to the particular fragment of the same complex epitope without cross-reactivity to other fragments. These data differentiate pCTL-2 receptors from effector CTL ones which are homogenous in specificity to a whole (single) complex epitope with variable degree of complementarity. A cardinal distinction of receptor repertoire between CTL, pCTL-2 and suppressor T cells specific to the same class I MHC molecule and alteration of the active site during pCTL-2 differentiation have been suggested.     

Functional analysis of cloned macrophage hybridomas. V. Induction of suppressor T cell responses

It has been suggested that macrophage-like accessory cells are involved in suppressor T cell (Ts) induction. To further analyze this issue, we obtained several cloned macrophage hybridoma cell lines by somatic cell fusion of the macrophage tumor P388D1 of DBA/2 (H-2d) origin with splenic adherent cells of CKB mice (H-2k). Several cloned lines displayed the serological and functional characteristics of macrophages. We evaluated the ability of these hybridomas to induce third order or effector Ts (Ts3) to suppress the contact sensitivity response against the hapten 4-hydroxy-3-nitrophenyl acetyl (NP). In contrast to the parental P388D1 and two other macrophage hybridomas, one macrophage hybridoma clone, termed 63, when conjugated with NP, induced Ts3, which suppressed contact sensitivity responses against NP but not DNFB, showing that the Ts3 were antigen specific. Macrophage hybridoma 63 could specifically induce Ts3 activity in either H-2k, H-2d, or H-2k/H-2d heterozygous hosts. Thus, macrophage hybridoma 63 functionally expressed major histocompatibility complex-related restricting determinants, and the fusion with cells from a H-2k macrophage donor caused a functional complementation of H-2d-related, Ts-inducing elements. The genetic restriction governing induction of Ts3 was controlled by genes that mapped to I-J region. Furthermore, NP-conjugated macrophage hybridoma 63 could serve as a target for elicitation of suppressor responses after administration of I-Jk, but not I-Jb, restricted suppressor factor. The data suggest that macrophage hybridomas represent a means to dissect heterogeneity within the macrophage population. The data also imply that the I-J determinants expressed on macrophages represent a ligand for the antigen receptor of Ts.     

Anti-H-2 antibodies induced by syngeneic immunization

Abstract. Alloreactive cytotoxic antibodies were induced in BALB/c mice by syngeneic immunization with normal lymphoid cells. Sixteen out of 41 mice produced antibodies with distinct anti-H-2 specificity. Anti-Kk antibodies were present in all positive sera, but the individual sera produced different reactivity patterns when tested on a panel of H-2 haplotypes. Absorption and immunoprecipitation experiments confirmed the H-2 specificity of the syngeneic sera. We hypothesize that virus-modified H-2d structures have triggered alloreactive B-cell clones to produce anti-H-2 antibodies.     

An IL 2-secreting T cell hybridoma that responds to a self class I histocompatibility antigen in the H-2D region

A self-reactive T cell hybridoma that secretes IL-2 in response to H-2d haplotype cells resulted from a fusion of BALB/cBy lymph node cells with the AKR thymoma BW5147. The lymph node cells used had been enriched for cells reactive to (TG)-A--L, but neither this antigen nor fetal calf serum were required for stimulation of the hybridoma designated 3DT52.5. The gene product responsible for stimulation mapped to the H-2D region. Allogeneic cells of the b, f, k, q, and s haplotypes failed to stimulate. Not all H-2d haplotype cells were effective stimulators of 3DT52.5. Peritoneal cells and splenic B cells were much more stimulatory than splenic T cells. Most tumor cell lines of H-2d derivation and of B cell or macrophage/monocyte lineage were stimulatory, whereas H-2d T cell lines were not. The capacity to stimulate 3DT52.5 did not correlate with the ability to stimulate I region-restricted hybridomas, or with the ability to be induced to stimulate such hybridomas. Stimulatory cell lines did not apparently produce a soluble factor required for stimulation, and negative cell lines were not inhibitory. The monoclonal antibody 27-11-13, which reacts with H-2D of the b, d, and q haplotypes, inhibited stimulation of 3DT52.5 but did not inhibit stimulation of the sibling hybridoma 3DT18.11, which responds to (TG)-A--L plus I-Ad. Conversely, the monoclonal anti-I-Ad antibody MK-D6 inhibited stimulation of 3DT18.11 but not 3DT52.5. Although it is clear that 3DT52.5 recognizes a class I antigen coded for in the H-2D region, the precise molecular nature of the antigen is unknown. The structure of the antigen receptor on this hybridoma may prove to be of interest when it can be compared with receptors found on T cell hybridomas restricted by class II histocompatibility antigens.     

The diversity of T cell receptors specific for self MHC gene products

Cytolytic and helper T cells exhibit, in addition to their specificity for foreign antigen, a restriction specificity for self MHC gene products. The present study was designed to assess the degree of diversity within the repertoire of receptors that are involved in T cell recognition of self MHC gene products. For this purpose, we generated a series of murine cytolytic T lymphocyte (CTL) clones specific for a hapten antigen and restricted to the self MHC gene product H-2Kb. An analysis of the hapten fine specificity of these clones by using hapten analogues revealed the presence of substantial diversity within the repertoire of CTL receptors specific for the hapten. The degree of diversity within the repertoire of self H-2 recognition structures on these clones was assessed by testing clones on panels of syngeneic, congenic H-2K disparate, and H-2Kb mutant target cells bearing varying amounts of antigen. A striking degree of heterogeneity in H-2K recognition was found among these H-2Kb restricted CTL. We estimate that there are probably a minimum of 65 different patterns of H-2K recognition among these clones. Our results suggest a high degree of diversity exists within the repertoire of self MHC recognition structures on antigen-specific T cells restricted to a single self MHC gene product.     

Dissection of the poly(glu60ala30tyr10) (GAT)-specific T-cell repertoire in H-21 k mice

We examined the antigen recognition of the class II major histocompatibility complex (MHC) of 45 poly(glu60 ala30 tyr10) (GAT)-reactive T-cell clones isolated by limiting dilution cloning of a pool of in vivo-primed and in vitro-restimulated A.TL lymph-node T cells. Each clone expressed the Thy-1.2+, Lyt-1+, Lyt-2-, LFA-1+, Ia-, and H-2Dd+ cell-surface phenotype and exhibited strict specificity for GAT on syngeneic antigen-presenting cells (APCs). The monitoring of the proliferative responses of these clones in the presence or absence of GAT, using APCs from strains with 11 independent H-2 haplotypes, revealed several distinct specificity patterns: (i) most (31 of 45, 73%) T-cell clones recognized GAT in a self-I-Ak-restricted manner; (ii) other alloreactive clones (5 of 45, 11%) were stimulated to proliferate, irrespective of the presence of GAT, in response to allodeterminants expressed on H-2s, H-2d, H-2f or H-2u spleen cells; (iii) a third T-cell clone subset (4 of 45, 9%) was activated by GAT in the context of not only self-I-Ak but also nonself restriction Ia determinants; and (iv) three clones (7%) exhibited a triple specificity, i.e., they recognized GAT in the context of self and nonself Ia determinants and were alloreactive. One of the latter clones responded to GAT in an apparently non-MHC-restricted manner and recognized an I-Ab allodeterminant. These data provide direct evidence that the antigen-specific and alloreactive T-cell repertoires overlap and that the self-MHC restriction of GAT-specific T-cell responses is not absolute in A.TL mice.     

Quantitative studies on the precursors of cytotoxic lymphocytes. II. Specificity of precursors responsive to alloantigens and to concanavalin A.

A microculture system was used to examine the specificity of cytotoxic T lymphocytes (CL) derived from single precursors. Our data indicate that clones derived from single precursors of CL (CLP) are specific. Thus, RNC mice (H-2k) simultaneously stimulated by both H-2d and H-2b antigens produce clones which are specific for either H-2b or H-2d but not for both. In lymph node (LN), the frequency of CLP giving rise to clones specific for H-2d and H-2b is 1/480 and 1/860, respectively. Clonal specificity is also maintained when Con A is used to activate the precursors. With a nonspecific assay of CL, it was found that 2.5% of the cells in LN are stimulated by Con A to produce clones of CL. Among the CLP stimulated by Con A, 2.1% of the clones are specific for H-2d alloantigens. An unexpected finding was that 18% of the clones produced by Con A stimulation lysed EL4 tumor cells, which carry H-2b; however, only a small proportion of these clones were specific for the H-2b alloantigen. The antigen on EL4 which accounts for the high response has not been characterized.     

Ir genes of different high responder haplotypes for staphylococcal nuclease are not allelic

The Ir gene controlling high responsiveness to staphylococcal nuclease in the H-2d haplotype has been mapped to the I-A subregion, in contrast to that in the H-2k and H-2a haplotypes, which maps in the I-B subregion. The nonallelic high responder genes also confer differences in fine specificity on the antibodies produced. This nonallelism of Ir genes for the same antigen in different haplotypes is consistent with Ir gene mechanisms involving associative recognition of antigen plus Ia by T lymphocytes. It further suggests that products of different subregions can perform the same function.     

Analysis of the negative allogeneic effect using B cells and helper T cell lines as an indicator system: B cells identified as target cells for suppression

The target cells for H-2b T lymphocytes mediating a negative allogeneic effect in vitro were analyzed by using carrier-specific helper T cell lines of H-2b, H-2d, or F1 origin and hapten-primed T-depleted spleen cells also expressing one or both of these haplotypes. The helper T cell lines were shown to be carrier specific and H-2b or H-2d restricted. Most importantly, the lines derived from H-2b homozygous mice were devoid of alloreactivity against H-2d and vice versa. Titration of naive H-2b T lymphocytes to the indicator cultures resulted in suppression of the secondary anti-DNP response of the indicator cells whenever the B cells expressed H-2d antigens. The lack of suppression observed in mixtures in which only the helper T cell lines expressed H-2d antigens was not reversed by the increased addition of naive H-2bxd cells, indicating that an insufficient amount of H-2d antigens present on the low number of helper T cells used did not account for this finding. Moreover, the polyclonal plaque-forming cell responses of F1 spleen cells to LPS were also suppressed by naive parental T cells. From these findings it is concluded that the suppressor T cells directly recognize and inhibit allogeneic B cells without the involvement of helper T cells. In addition, it was shown that the suppression of secondary anti-hapten responses by naive allogeneic T cells is blocked by monoclonal anti-Lyt-2 antibody added at the onset of culture. Addition late in culture had no effect, pointing to a functional role of the Lyt-2-bearing structure at an early stage of the suppressive events resulting in the negative allogeneic effect.     

T cell recognition of Mlsc. I. Influence of MHC gene products in Mlsc-specific T cell recognition

Monospecific T cell clones have been proven to be powerful tools for the characterization of T cell recognition in many Ag-specific as well as allo-specific T cell responses. In this report, in order to elucidate the mechanism of T cell recognition of minor stimulating locus Ag (Mlsc) determinants, Mlsc-specific cloned T cells were employed together with primary T cell responses to clarify the role of MHC-gene products in Mlsc-specific T cell recognition. The results indicated that T cells recognize Mlsc determinants in conjunction with I-region MHC gene products. Moreover, certain MHC haplotypes (e.g., H-2a and H-2k) appear to function efficiently in the "presentation" of Mlsc, whereas other haplotypes (e.g., H-2b and H-2q) function poorly if at all in presenting Mlsc. Experiments with the use of stimulators derived from F1 hybrids between the low stimulatory H-2b, Mlsc strain, C3H.SW, and a panel of Mlsb, H-2-different or intra-H-2 recombinant strains strongly suggested that expression of E alpha E beta molecules on stimulators plays a critical role for Mlsc stimulation. The functional importance of the E alpha E beta product in Mlsc recognition was further demonstrated by the ability of anti-E alpha monoclonal antibody to inhibit the response of cloned Mlsc-specific T cells. Inhibition of the same Mlsc-specific response by anti-A beta k antibody suggests that the A beta product may also play a role in T cell responses to Mlsc.     

Frequency and cross-reactivity od cytolytic T lymphocyte precursors reacting against male alloantigens

It is well established that cytotoxic T lymphocytes (CTL) specific for the male minor histocompatibility antigen (H-Y) are generated by restimulation in vitro of in vivo primed spleen cells from C57BL/6 (H-2b) female mice with syngeneic male spleen cells. When tested on target cells from H-2 different strains, the male-specific C57BL/6 CTL populations exhibited significant lysis of DBA/2 (H-2d), A (H-2a), but not C3H (H-2k), male and female target cells. In an attempt to document this cross-reactivity further at the clonal level, a sensitive technique of limiting dilution analysis was used to determine the specificity of C57BL/6 individual CTL precursors (CTL-P) reactive against the male antigen. The mean frequency of anti-H-Y CTL-P in spleens of primed female mice was about 1/3500. Between one-third to one-tenth of these CTL-P produced a progeny that cross-reacted with H-2d (allogeneic) female target cells. These findings were confirmed by the analysis of the reactivity pattern exhibited by male-specific CTL clones derived by limiting dilution. Of 99 clones tested, 13 were found to cross-react with female DBA/2 target cells. These results thus indicate that a relatively large proportion (greater than 10%) of H-2b CTL-P directed against the H-Y antigen cross-react with target cells expressing H-2d alloantigens in the absence of H-Y antigen.     

Ia antigens: markers of specific T suppressors immune to H-2 complex antigens

Two antisera to Ia antigens, products of the H-2 complex I-Cd and I-JkEk subregions, respectively, have been obtained by immunisation of the F1 hybrids of recombinant strains of mice. These antisera are shown to display the 50 per cent cytotoxic effect in vitro in the presence of complement upon lymphocyte populations immune to the H-2 complex antigens and enriched for specific suppressor T cells (SSC) by fractionation on the monolayer of target cells. The specificity of anti-Ia cytotoxins is shown by the cross antibody absorption with T- and B-cells of mice originated from the recombinant H-2 haplotypes and bearing either particular I-Cd, I-Jk and I-Ek antigens, or their combinations. Anti-I-Cd cytotoxins are found to react with both B and T cells at a different rate, and the anti-I-JkEk serum contains two antibody types directed to I-Ek and I-Jk products, respectively, the latter being able to react preferently with T cells. Although both antisera do inactivate the in vitro SSC function in the presence of complement at a similar degree, the inactivating action of the anti-I-Cd serum, but not that of the anti-I-JkEk serum, occurs without complement. SSC are established to bear both Ia-antigens, I-J and I-C on the same cell, as demonstrated by the cross antibody absorption and variation of the H-2 origin of SSC. These two markers are suggested to function differently in the SSC immune to the H-2 antigens and the I-C antigen expression on the SSC surface is presumed to be required for their interaction with the inhibited responder T cells proliferating in MLC.     

Functional analysis of cloned macrophage hybridomas. VI. Differential ability to induce immunity or suppression

We previously screened a series of macrophage hybridomas derived from fusion of P388D1 (H-2d) tumor cells with CKB (H-2k) splenic adherent cells for their ability to induce I-J restricted Ts cell responses. One Ia+ macrophage clone (63) consistently induced Ag-specific, I-J-restricted Ts. To evaluate whether macrophage hybridoma 63 also induced delayed-type hypersensitivity (DTH) immunity, mice were immunized with hapten-coupled macrophage hybridoma cells. Hapten-coupled splenic adherent cells and control macrophage hybridomas induced significant primary DTH responses, whereas hapten-coupled macrophage 63 induced little or no immunity when injected into H-2 compatible hosts. However, macrophage hybridoma 63 specifically activated I-Ak, I-Ad, or I-Ed restricted T cell hybridomas/clones, in vitro in the presence of appropriate Ag. Three different strategies designed to eliminate suppressor cell activity were successfully used to demonstrate that hapten-coupled macrophage 63 could also induce in vivo immunity. First, after immunization with hapten-coupled macrophages, mice were treated with cyclophosphamide. Second, macrophage 63 was treated with anti-IJ idiotype antibody before 4-hydroxy-3-nitrophenyl acetyl hapten (NP) coupling. Finally, haptenated macrophages were injected into I-A compatible but I-J incompatible recipients. These protocols are known to inhibit the induction of Ts activity, thus these results indirectly suggest that there is stimultaneous generation of Ts activity in vivo. The latter hypothesis was tested in adoptive transfer experiments. Transfer of lymph node cells from NP-63 primed B10.BR (H-2k) mice induced immunity in naive 4R animals, whereas the same number of immune cells suppressed NP-induced DTH responses in 5R mice. The combined results indicate that a cloned macrophage line can activate both Th and Ts cells. Macrophages which induce Ts activity may be responsible for maintaining the balance of immunity vs suppression. The data support the hypothesis that IJ interacting molecules (IJ-IM) expressed on macrophages are critical for induction of suppressor cell activity.     

Suppressor T cells arising in mice undergoing a graft-vs-host response.

We investigated the ability of mice to generate antibody-forming cells when undergoing a graft-vs-host reaction. (C57BL/6 X DBA/2)F1 mice (BDF1) injected with C57BL/6 spleen cells generated suppressor T cells which inhibit antibody synthesis by BDF1 spleen cells in vitro. These T cells arose from the donor inoculum. They differ from helper T cells in size and they act directly on antigen reactive B cells. The suppressor T cells were specifically directed against components of the H-2 region of the reciprocal parental strain (DBA/2 = H-2d) in the hybrid F1 mouse.     

Establishment and characterization of murine macrophage hybrids

Proteose peptone-induced peritoneal macrophages from CBA/J (H-2k) mice have been fused to a hypoxanthine phosphoribosyltransferase-negative variant of the P388D1 (H-2d) murine macrophage cell line. Six hybrid clones were isolated following HAT selection and further characterized. Five of the six clones express class I antigens of both parental haplotypes by microelisa and by flow cytometric analysis. Class II antigen expression of both haplotypes was apparent following a 72-hr incubation of the hybrids with concanavalin A-stimulated rat spleen cell supernatant. However, I-Ad was expressed in all hybrids to a greater extent than I-Ak. Three clones with the highest level of I-Ak expression, E5, C2, and C4, were capable of antigen presentation to the I-Ak-restricted T-cell line, D10.G4.1. LPS induction of the hybrids resulted in a 2- to 15-fold increase in the amount of IL-1 produced relative to the P388D1 parent. Finally, in distinction to P388D1, all hybrids demonstrated increased Fc-mediated erythrophagocytosis of chromium-labeled antibody-coated erythrocytes. These murine macrophage hybrids appear stable and should serve as useful models in understanding the regulation of macrophage function.     

High frequency and nonrandom distribution of alloreactivity in T cell clones selected for recognition of foreign antigen in association with self class II molecules

Previous studies have demonstrated that a single T cell clone can respond to both a foreign antigen in the context of self major histocompatibility complex (MHC)-encoded molecules (self plus X) and to an allogeneic class I or class II molecule in the absence of antigen (non-self). We have used limiting dilution of T cells obtained from the draining lymph nodes of antigen-primed B10.A mice to establish a large number of T cell clones that recognize either GAT, pigeon cytochrome c, or sheep insulin in association with syngeneic antigen-presenting cells. Sixty-two antigen-specific T cell clones were assayed for their ability to proliferate in response to a panel of nine different allogeneic haplotypes. Of these, 38 (61%) responded to at least one allogeneic haplotype, and 15 of the 38 (39%) responded to more than one allogeneic stimulator. In addition, the patterns of alloreactivity varied with the immunizing antigen. The GAT-specific T cells had at least one responder to every haplotype tested, although H-2u-responsive T cell clones were the most common. In contrast, no pigeon cytochrome c-specific T cells responded to stimulators of the H-2u haplotype, but rather predominantly responded to H-2t4/H-2s and H-2i5/H-2b. Finally, sheep insulin-reactive T cell clones preferentially responded to H-2u stimulators, although stimulation by antigen-presenting cells of the H-2p and H-2q haplotypes was also common. A chi 2 analysis of the data demonstrated that the dependence of the pattern of alloreactivity observed upon the antigen used for immunization was statistically significant (p less than 0.01). The high frequency of alloreactivity found in antigen-specific T cell clones is discussed, as well as the implications that the antigen-dependent skewing of the distribution of alloreactivity have for a one-receptor model vs a two-receptor model of T cell recognition.     

Alloreactive cloned T cell lines. VII. Comparison of the kinetics of IL 2 release stimulated by alloantigen or Con A

Injection of poly(Glu50Tyr50)(GT) into B10.BR (H-2k) mice induces GT-specific suppressor T cells and a T cell-derived suppressor factor (TsF1), which in turn induces a second-order suppressor T cell (TS2). In the present study, we show that B10.BR GT-TSF1 is composed of separate I-Jk and idiotype-bearing chains linked by disulfide bond(s). Functional suppressive activity requires both chains to be in association. Neither chain alone can induce TS2, indicating that both chains must be seen in association and suggesting a single cellular target for the two chains. Experiments designed to interchange I-J-bearing chains of GT-TSF1 derived from different H-2 haplotypes indicate that only the homologous I-J and idiotype-bearing chains can reassociate into a suppressive moiety. These experiments may imply heterogeneity of I-J region gene products.